Rotary hook for sewing machines



Mrch 31, 19 3s. c. c. SMITH 2,035,928

RO'Y'ARY HOOK FOR SEWING MACHINES Filed Oct. 5, 1934 Patented Mar. 31, 1936 PATN FFHQE ROTARY HOOK FOR SEWING MACHINES Clarence C. Smith, Chicago, 111., assignor to Union Special Machine Company, Chicago, 111., a corporation of Illinois Application October 5, 1934, Serial No. 747,053

6 Claims.

The present invention relates to new and useful improvements in a rotary hook for a lock stitch sewing machine and more particularly to a rotary hook construction which affords novel lubricating means for the interengaging parts between the rotary hook and the stationary bobbin casing.

An object of the present invention is to provide a rotary hook wherein means are provided for directing lubricant from a point adjacent the axis of the hook exteriorly of the rear face thereof to a the interengaging parts between the rotary hook and the bobbin casing, and wherein said means may be attached to the rotary hook with very little change therein and may be readily removed for cleaning.

A further object of the invention is to provide, in a rotary hook, means for lubricating the interengaging parts between the rotary hook and the stationary bobbin casing wherein a tube leading from a recess at the axis of the rotary hook to an inclined surface on the inner face of the hook rim is adapted to form a conduit through which oil may be caused to flow by centrifugal force to the interengaging parts.

The above and other objects of the invention will in part be obvious and will be hereinafter more fully pointed out.

In the accompanying drawing:

Figure 1 is a side view in section showing the assembled rotary hook, bobbin, bobbin casing and a portion of the bearing and actuating shaft.

Fig; 2 is a rear View taken along line 22 of Fi 1.

' The invention relates generally to lubricating means for the interengaging parts between the rotary hook and the stationary bobbin casing. v The rotary hook is fixed to the end of a rotating shaft and the bobbin and the bobbin casing are mounted within and supported by the rotary hook. The bobbin casing is provided with a circumferential rib which engages a groove or raceway in the hook and thus lateral movement between the bobbin casing and the rotary hook is prevented. A portion of the bobbin casing engages a fixed part of the sewing machine in order to prevent rotation of the casing within the rotary hook. Extending longitudinally and centrally of the rotating shaft is a port which is open at the end of the shaft adjacent the hook and which is preferably provided with wicking. The shaft terminates short of the inner face of the rotary hook in order to provide a recess at the axis thereof. A sleeve or bushing, in which the shaft rotates, is provided with an opening which registers with an oil hole from which oil may be admitted to the port in the shaft through a suitable opening therein. Thus the lubricating oil may be fed to the recess formed in the hub of the rotary hook. The hub of the rotary hook is provided with a radial port communicating with the recess there- 5 in. One end of a tube is fitted in this port and the opposite end thereof is disposed within an overhanging part of the hook rim, the surface of which is inclined toward the interengaging parts between the rotary hook and the bobbin casing so that oil passing through the tube by centrifugal force will likewise follow this inclined surface on the hook rim to the interengaging parts. It will be seen that the thread passing between the rotary hook and the bobbin casing will not come in contact with the oil tube and so will not become soiled.

Referring more in detail tothe accompanying drawing, the invention is shown as applied to a sewing machine having a work support I0 which is provided with a depending bearing bracket in which is mounted a bushing ii. The actuating shaft I2 is mounted within the bushing II and carries at the end thereof a rotary hook I3. The actuating shaft l2 may be driven by suitable intermeshing gears, as shown in the co-pending application of George Sauer, Serial No. 688,512, filed September '7, 1933, and described in detail in the co-pending application of Norman V. Christensen, et al., Serial No. 670,186, filed May 9, 1933. The shaft l2 may also be driven in the manner shown and described in the co-pending applica tions of George Sauer, Serial Nos. 716,415 and 716,416, filed March 19, 1934. The particular manner in which the rotary hook is driven forms no part of the present invention.

The rotary hook i3 is of the usual cup-shaped construction with portions cut away to form spaced radial webs or spokes 14 which are formed as a part of the hub it. One side wall of the cup is shaped to provide a book which is adapted to enter the needle thread loop and carry the same about the bobbin casing H5 which is alsocupshaped and is adapted to receive and support a bobbin I] therein. The bobbin I7 is held within the bobbin casing by a cover or carrier Hi. The bobbin casing i6 is provided with a circumferential rib I9 which fits within a groove or raceway 20 in the rotary hook. The rib l 9 and raceway 20 form interengaging parts to prevent lateral movement of the bobbin casing within the rotary hook. The bobbin casing is provided with a projecting portion 2| which engages a fixed part of the sewing machine in order to prevent the rotation thereof. The rotary hook operates in the usual manner and further description thereof is not considered necessary.

The present invention relates more particularly to a means for lubricating the interengaging parts between the bobbin casing and the rotary hook. When the hub l5 of the rotary hook is placed on the shaft 12 and secured thereto by one or more set screws 22, there is preferably left a space between the end of the shaft and the inner face of the rotary hook, thus forming a recess 23 which is closed at the inner face of the rotary hook by a closure plate 24 in order to provide a closed recess to retain oil therein and prevent it from reaching the inner face of the rotary hook.

In the drawing, by way of illustration, the hub I5 is shown as provided with a port 25 which extends radially therethrough and which communicates with the recess 23. One end of an oil tube 28 is mounted in the port 25 in the hub 55. The free end of the tube 26 is bent slightly to underlie an overhanging portion 27 on the hook rim between two spokes. The inner face 28 of the hook rim is inclined and leads to the raceway 20. While only one tube and one port 25 have been shown, it is to be clearly understood that a plurality of the sarne may be employed if so desired.

The actuating shaft 12 is provided with a central bore 29 which opens into the recess 23 and is preferably filled with wicking. The bushing l I is provided with an opening 38 which registers with an oil hole 3| in the bearing bracket of the machine. Thus oil may be admitted through the oil hole 3! and the opening 30 in the bushing and it will then pass into the bore 29 through. an opening 32 in the shaft l2. The oil will then flow into the recess 23 from which it will be thrown by centrifugal force through the port 25 and tube 26 to the inclined surface 28 from which it will reach the raceway 26 so that, as the hook rotates, the interengaging parts between the rotary hook and the bobbin casing, that is, the raceway 2i] and the rib I9, will be efficiently lubricated without any danger of soiling the thread. It is to be noted that the hook may be easily cleaned so that the danger of clogging of the oil tube is prevented.

From the foregoing description it will be seen that the tube 23 may be easily connected to the hub of the rotary hook without making any changes in the spokes of the hook and that it may be removed conveniently for cleaning.

It is to be clearly understood that minor changes in the details of construction and arrangement of parts may be made without departing from the scope of the invention as set forth in the appended claims.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a sewing machine, the combination of a rotary book, a stationary bobbin casing supported therein, said hook and easing having interengaging parts to prevent relative lateral movement therebetween, and detachable means located exteriorly of the rear face of said hook and rotatable therewith and having a conduit therethrough for directing lubricant from a point adjacent the axis of the hook to the inner face of the hook rim whereby to lubricate said intereng'aging parts.

2. In a sewing machine, the combination of a rotary hook having a hub, a rim portion and spaced radial webs connecting said hub and rim portion, of a stationary bobbin casing supported by said hook, said hook and casing having interengaging parts to prevent relative lateral movement therebetween, and means connected to said hub exteriorly of said webs for directing lubricant to the inner face of said rim between two of said webs whereby to lubricate said interengaging parts.

3. In a sewing machine, the combination of a rotary hook having a hub, a rim portion and a connecting Web portion, of a stationary bobbin casing supported therein, said hook and casing having interengaging parts to prevent relative lateral movement therebetween, and means for directing lubricant from a supply adjacent the axis of the hook to said interengaging parts and including a tube disposed exteriorly of said. web portion and leading from said supply to a point adjacent said interengaging parts.

4. In a sewing machine, the combination of a rotary hook, a stationary bobbin casing supported therein, said hook and easing having interengaging parts to prevent relative lateral movement therebetween, said hook having a recess at the axis thereof, and means for directing lubricant from said recess to said interengaging parts and including a tube mounted on the hub of the hook communicating with said recess.

5. In a sewing machine, the combination of a rotary hook having a hub, a rim portion and spaced radial webs connecting said hub and rim portion, of a stationary bobbin casing supported within said rim portion, said hook and easing having interengaging parts to prevent relative lateral movement therebetween, said rim having an inclined surface between two of said webs, and means for directing lubricant from a supply adjacent the axis of said hook to said inclined surface whereby to lubricate said interengaging parts and including a tube mounted in said hub and having the free end thereof adjacent said inclined surface.

6. In a sewing machine, the combination of a rotary hook having a hub, a rim portion and spaced radial webs connecting said hub and said rim portion, of a stationary bobbin casing supported by said hook, said hook and casing having interengaging parts to prevent relative lateral movement therebetween, and means for directing lubricant from a supply in said hub to said interengaging parts and including a tubular member having one end mounted in said hub and having the opposite end thereof bent inwardly to lie adjacent the inner face of said rim portion between two of said webs.

CLARENCE C. SMITH.

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